1. Field of the Invention
The present invention relates to an optical device and a projector.
2. Description of the Related Art
Projectors including an optical modulator for modulating light beams emitted from a light source according to image information supplied to the projector and a projection optical device for enlarging and projecting the light beam modulated by the optical modulator are known.
An active matrix drive type optical modulator formed by using a pair of substrate and an electro-optical material such as liquid crystal contained between the substrates in a hermetically sealed state is generally used for the optical modulator. More specifically, the paired substrates of the optical modulator include a drive substrate on which data lines for applying a drive voltage to the liquid crystal, scanning lines, switching elements, pixel electrodes, etc. are arranged and an opposite electrode on which a common electrode, a black mask, etc. are arranged.
Additionally, an incident-side polarization plate and an irradiation-side polarizator that are adapted to transmit lights beam having a predetermined polarization axis are arranged respectively at the light-incident side and the light-irradiation side.
When light beams emitted from the light source are irradiated onto the optical modulator, the temperature of the optical modulator is apt to rise because of the absorption of light of the liquid crystal layer, that of the data lines and the scanning lines formed on the drive substrate and that of the black matrix formed on the opposite substrate. Additionally, of the light beams emitted from the light source and the light beams transmitted through the optical modulator, those that do not have a predetermined polarization axis are absorbed by polarization plates so that the polarization plates are apt to generate heat.
Thus, projectors having such an optical element in the inside and equipped with a cooling device using cooling fluid have been proposed for the purpose of alleviating the temperature rise of the optical element (see, for example, Japanese Patent Laid-Open Publication No. Hei 1-159684).
The cooling device as described in the above-cited patent document has a cooling chamber adapted to support the optical modulator and the polarization plates in a mutually separated state and filled with cooling fluid in the inside. The cooling chamber is connected to a radiator and held in communication with a radiator and a fluid pump typically by way of tubes that allows cooling fluid to flow through the inside thereof. Thus, the cooling fluid in the inside circulates through the flow path of the cooling chamber—radiator—fluid pump—cooling chamber that are connected by tubes or the like. With this arrangement, the heat generated in the optical modulator and the polarization plates by the light beams emitted from the light source is directly discharged to the cooling fluid.
However, the projector described in the above-cited patent document is accompanied by a problem that it has large dimensions and hence does not allow easy handling because the cooling chamber, the radiator and the fluid pump are separated from each other but connected to each other by tubes or the like in order to make them communicate with each other.
Additionally, if the cooling device is equipped with a tank for temporarily storing cooling fluid in order to raise the volume of cooling fluid that is used in the cooling device and improve the efficiency of cooling the optical element, the dimensions of the cooling device increase further to make it less handleable.
Particularly, when plural optical modulators are used, the above problem becomes more remarkable.